The present invention relates to an optical disk controller that performs processing such as modulation on a signal obtained from a pickup by reading data recorded on an optical disk.
In recent years, development of optical disk devices for DVD-ROMs, DVD-RAMs, in succession to those for CD-ROMs, has made progress. Many of such optical disk devices are implemented by the combination of an optical disk controller that performs a series of data processing including modulation, error correction, buffering, and transfer to host and a system controller that controls components of the optical disk device such as a pickup and a servo.
FIG. 10 shows an optical disk device including a conventional optical disk controller. Referring to FIG. 10, the optical disk device includes: a spindle motor 101 for rotating an optical disk 100; a pickup 102 for reading data from the optical disk 100 by radiating the optical disk 100 with laser light; a servo 103 for positioning the pickup 102; an optical disk controller (ODC) 710 for performing signal processing; and a system controller 720 for controlling the operation of the entire system.
The optical disk controller 710 includes a command interpreter 711, a demodulator 712, an error correction section 713, a data buffer 714, a host interface 715, and a status generator 716.
A host PC 730 sends a command to the optical disk device requesting data read from the optical disk 100. On receipt of the data read command via the host interface 715, the system controller 720 controls the spindle motor 101 to rotate the optical disk 100 and the servo 103 to move the pickup 102 to a target sector. The system controller 720 then issues command READ to the optical disk controller 710.
On receipt of the command READ, the command interpreter 711 instructs the demodulator 712 to read specified sectors. The demodulator 712 monitors data read by the pickup 702 and, when recognizing data of a head sector, sends the data of the sector to the error correction section 713. The error correction section 713 executes error correction for the data output from the demodulator 712. The error-corrected data is then temporarily stored in the data buffer 714.
The status generator 716 generates a status report or “status” for the data based on the error correction results received from the error correction section 713. FIG. 11 shows examples of generated status reports, each of which is composed of items of information category, factor, and auxiliary information. The information category indicates whether the issued command was “continued”, “normally ended”, or “abnormally ended”. The factor indicates the state of the current sector. If any problem arises, information on the problem is added to this item. The auxiliary information includes the current sector ID and the buffer page number on which the error-corrected data has been stored.
The status generator 716 generates a status report every time data of each sector is read, and outputs the results to the system controller 720. The factor of the status report is “normal” for the sector of which data has been normally corrected. For the sector of which data has failed to be normally read during reading of the sector, the factor of the status report includes relevant information, so that the system controller 720 is notified of the information.
Thus, the optical disk controller 710 generates the status report representative of the inner state thereof every error correction, thereby enabling the system controller 720 to keep track of the operation of the optical disk controller 710. Based on the status report received, the system controller 720 can determine whether read operation be continued or aborted. In this way, proper read processing is realized.
In optical disk devices, one of factors for determining drive performance is the rotational speed of the disk. As the rotational speed of the disk is higher, the data read/write time is shorter and the data processing size per unit time is greater. Therefore, nowadays, operation at a higher rotational speed is requested for optical disk devices.
In the conventional status report output procedure, as the rotational speed of the disk is higher, the period of status report output becomes shorter. This reduces the time allowance given for determining whether the processing be continued or aborted based on a received status report after the status report is received. Consequently, as the rotational speed of the disk increases, the burden of the system controller becomes excessively large.